853e126ce3
In large code model, the address of GOT is calculated by the static linker via R_X86_GOTPC64 reloc applied against a MOVABSQ instruction. In the final binary, it can be disassembled as a regular immediate, but because such immediate is the result of PC-relative pointer arithmetic, we need to parse this relocation and update this calculation whenever we move code, otherwise we break the code trying to read GOT. A test case showing how GOT is accessed was provided. Reviewed By: #bolt, maksfb Differential Revision: https://reviews.llvm.org/D158911
56 lines
1.1 KiB
ArmAsm
56 lines
1.1 KiB
ArmAsm
# REQUIRES: system-linux
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# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
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# RUN: %s -o %t.o
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# RUN: %clang %cflags -no-pie %t.o -o %t.exe -Wl,-q
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# RUN: llvm-bolt %t.exe --funcs init_impls --lite \
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# RUN: -o %t.bolted
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# RUN: %t.bolted | FileCheck %s
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.section .rodata.str1.1,"aMS",@progbits,1
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.LC2:
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.string "Hello, world\n"
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.text
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.p2align 4
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.globl init_impls
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.type init_impls, @function
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init_impls:
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.cfi_startproc
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push %rbp
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mov %rsp,%rbp
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push %r15
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push %rbx
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sub $0x8,%rsp
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1:
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lea 1b(%rip),%rbx
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# R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_+0x9
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movabsq $_GLOBAL_OFFSET_TABLE_-1b, %r11
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add %r11,%rbx
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# R_X86_64_GOTOFF64 .LC2
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movabs $.LC2@gotoff,%rax
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lea (%rbx,%rax,1),%rax
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mov %rax,%rdi
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mov %rbx,%r15
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# R_X86_64_PLTOFF64 puts
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movabs $puts@pltoff,%rax
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add %rbx,%rax
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call *%rax
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add $0x8,%rsp
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pop %rbx
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pop %r15
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pop %rbp
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retq
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.cfi_endproc
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.size init_impls, .-init_impls
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.globl main
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.type main, @function
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.p2align 4
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main:
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callq init_impls
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xorq %rax, %rax
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ret
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# CHECK: Hello, world
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